The present invention relates to a disposable one-piece seat liner including means to accommodate the seat belts of a wide variety of car seats, strollers, carriers, highchairs and the like. The seat liner is formed from a layer of absorbent cellulosic fibers or the like possessing sufficient integrity that it does not abrade during normal use bonded to a flexible moisture repellant backing sheet. One advantage of the present invention over prior art disposable seat liners such as that described in U.S. Pat. No. 4,621,004 is that it can be manufactured much more efficiently.